Versions

Betweenlands version:

The Betweenlands v3.4.4 + Server 3.4.4

Forge version:

Minecraft Forge 1.12.2 - 14.23.5.2814

Singleplayer or Multiplayer:

Multiplayer Server utilitising SPONGEFORGE 1.12.2-14.23.5.2768-7.1.6-RC3583

Installed mods:

https://www.technicpack.net/modpack/one-life-popular-smp.1297373

Link to full crash log

https://paste.dimdev.org/amerocoren.mccrash

Description of the problem

How to reproduce:

1. Fight your way up the Wight Fortress
2. Get to the Eye (that teleports you to final boss)
3. Stare at the eye (that teleports you to final boss)
4. Crash, become depressed.
5. Can't join server back because it will just continually crash.
6. Reset your position, do /back and it doesn't spawn the boss but teleports you??

Expected result:

to be teleported up to the top and fight the boss like that mfkin king

Actual result:

Stare at the eye, fucking crash.

Pictures:

unneeded.

Upon trying to spawn the "Primordial Malevolence" using the spawn egg it causes a new crash log seen below.

https://paste.dimdev.org/eyewilogex.mccrash

Thanks for the report.
This is not a problem on our side, it's caused by another mod. I suspect it's MoCreatures because that mod is known to cause this exact problem for several mods.